A proportional magnet of the above mentioned construction for use in a proportional pressure control valve has been disclosed, for example, in the Applicant's DE 199 04 901. In the publication is described one valve which is used for control of clutches in automatic motor vehicle mechanical transmissions (CE pressure regulator).
A similar proportional pressure-control valve, which likewise contains a proportional magnet of the above mentioned design, has been disclosed in the Applicant's DE 199 04 902. This document specially refers to valves which are used as direct control valves for the control of clutches in an automatic motor vehicle mechanical transmission (ZF pressure regulator).
These applications have respectively described proportional or hold magnets and switching magnets which implement a defined transition from the control region to a hold region or to a magnetic hold position. According to the prior art, this defined transition is attained by the fact that by the magnet characteristic known per se with great magnetic forces in small air gaps between the magnet armature and the magnet core and by suitable magnet layout, it is possible to adjust a coil current or a “snap current” under which the control region of the magnet is quickly overwound, that is, the magnet armature “snaps” from the control region to the hold position and the magnet armature is retained in the hold position in the region of the high magnetic force.
A movement in opposite direction, namely, the loosening of the proportional magnet from the hold region or the hold position and passage to the control region, hitherto could not be satisfactorily controlled according to the prior art.
The problem on which this invention is based is to outline a method which recognizes the movements of the magnet armature and thus can be used for defined disconnection of the proportional magnet or for loosening from the hold position a control element of a switch or proportional pressure-control valve connected therewith in order thus to implement a defined transition from the hold region, especially the hold position, to the control region. Also a problem to be solved by this invention is to outline a proportional magnet for carrying out the method, the same as a proportional pressure-control valve which contains such a proportional magnet.
This problem is solved with a method, a proportional magnet and a proportional pressure control valve.